Dynamoelectric machine provided with gas lubricated bearings



Nov. 12, 1963 B. STERNLICHT DYNAMOELECTRIC MACHINE PROVIDED WITH GASLUBRICATED BEARINGS 2 Sheets-Sheet 1 Filed June 2'7, 1961 0 ImW W 9 bHis Attorney.

Nov. 12, 1963 B. STERNLICHT DYNAMOELECTRIC MACHINE PROVIDED WITH GASLUBRICATED BEARINGS '2 Sheets$heet 2 Filed June 27, 1961 Inventor-.-

Bervo Stern/[ch11 by 4 1 5 His Attorney- United States Patent Ofifice3,116,823 DYNAMOIELEC'IRIC MAQHINE IROVIDED WITH GAS LUBRICA'IEDBEARINGS Reno fiterniieht, Schenectady, N.Y., assignor to GeneralElectric Company, a corporation of New York Filed .Iune 27, 1961, Ser-No. 120,089 Claims. (Cl. 310-57) The present invention relates todynamoelectric machines and, more particularly, to electric motor drivenfans.

The physical size and shape of an electric motor driven apparatus isoften determined by the cumulative functions supplied by variouselements of the apparatus. In the usual induction motor driven fan, forexample, the length of the apparatus is to a large degree determined bythe functions associated with the rotor. Generally, the rotor has thefollowing functions incorporated therein: the electromotive function foractuating the device, bearings for rotatably supporting the rotor, andcoupling means for attaching the vanes or other air moving means. Theelectromotive portion of the apparatus is determined in terms of size byfactors such as running and starting requirements. This considerationfurther suggests the size and character of the bearings and also theamount of lubricant reservoir space required to supply lubricant to thebearings.

During designing, these factors are considered and reconciled withcompetitive considerations to determine the nature of the finalcommercial apparatus. For example, because of market considerations, thesize of the electromotive portion of the apparatus may be modified andboundary lubrication may be resorted to in the bearings despite theundesirable aspects of rubbing contact in a bearing construction. Thesecompromises result in a reduced life span for the apparatus, andfurther, in the possibility of a less satisfactory apparatus because ofincreased noise, vibration, and wear.

The chief object of the present invention is to provide an improveddynamoelectric machine.

An object of the invention is to provide an improved compact motordriven fan.

A further object of the invention is to provide a dynamoelectric machinehaving improved bearing means.

Another object of the invention is to provide an improved dynamoelectricmachine having gas lubricated bearings located in the magnetic gap ofthe machine.

A still further object of the invention is to provide an improveddynamoelectric machine having a rotor which envelops the stator, andfurther having bearing means located in the magnetic gap between therotor and the stator.

These and other objects of my invention may be more readily perceivedfrom the following description.

One of the features of the present invention is an improved fan whichhas air or gas propelling vanes mounted on a rotor which envelops thestator. Gas lubricated bearings may be located in the magnetic gapbetween the stator and the rotor and atmospheric air may be supplied tothe bearings in the magnetic gap through suitable grooves provided'inthrust bearings located adjacent the ends of the rotor. H

The attached drawings illustrate preferred embodiments of the invention,in which:

FIGURE 1 is a sectional View of a motor driven fan employing the presentinvention;

FIGURE 2 is a sectional view taken through line 22 in FIGURE 1 showingthe rotor construction employed in the apparatus.

FIGURE 3 is a sectional view of the apparatus shown in FIGURE 1 takenthrough line 3-3 showing the sur- 3,110,828 Patented Nov. 12, 1963 faceconfiguration of the thrust bearing utilized in the apparatus in FIGURE1;

FIGURE 4 is an enlarged sectional view of a portion of the thrustbearing shown in FIGURE 3 taken through line 4-4;

FIGURE 5 is a view of another embodiment of a thrust bearing for use inthe apparatus in FIGURE 1; and

FIGURE 6 is a diagrammatic view showing the hydrodynamic forcesgenerated in the magnetic gap of the apparatus shown in FIGURE 1.

In FIGURE 1 there is shown an induction motor which may comprise a rotorwhich envelops a stator having air bearing means on the magnetic gaptherebetween for supporting said rotor. Rotor 2 may comprise asubstantially cylindrical member having an annular flange 3 formounting, by bolt means or otherwise, vanes 4 for propelling air orother gaseous medium. On each end of rotor 2 may be located suitableplanar thrust journal surfaces 5 and cylindrical member 2 may include aninner cylindrical journal surface 6 adapted to engage the bearingsurface 7 of stator 9 in a manner more fully described hereinafter.Stator 9 may include a laminated portion 8 having suitable windings 10and in view of the need for a magnetic gap between journal 6 and bearing7, the stator may be suitably coated with a non-magnetic material suchas a silicone plastic impregnated with graphite to provide lubricatingqualities for use in a manner more fully described hereinafter.Laminated portion 8 of stator 9 may be mounted on a stationary shaftportion 11 extending from each end thereof which may be connected tostationary vertical supports 12. On one side of shaft 11 there may befurnished a passage 13 to permit electrical connections 14 to passtherethrough to permit the supply of electrical power to windings 10.

In the present embodiment, stator 9 has associated therewith thrustbearing members 16 on each side of rotor 2 to support reactive forcesgenerated by vanes 4 propelling air or other gaseous medium. Each ofsaid thrust bearing constructions may be supported on stationary shaft11 and have bearing surfaces 17 adapted to coact with journal surfaces'5 on the ends of rotor 2. The nature of thrust bearing surfaces 17 ismore fully described hereinafter.

In FIGURE 2 there is shown a sectional view taken through line 22 inFIGURE 1 which shows rotor 2 as comprising a cylindrical shape memberhaving an inner cylindrical opening which defines journal surface 6. The

.outer periphery of rotor 2 may be provided with flange 3 havingsuitable bolt holes therein for supporting a plu- 'rality of airpropelling vanes 4. In this construction, the

rotor may be fabricated of solid ferrous material and may have locatedadjacent and concentric with the opening defined by the journal surface6 a plurality of rotor bars 19 fabricated of a material such as copperor aluminum. These rotor bars 19 are annularly disposed parallel to theaxis of the rotor. The nature and operation of this type of inductionmotor is conventional and well known in the art.

In FIGURE 3 there is shown a sectional view of the apparatus shown inFIGURE 1 taken through line 3-3 .to illustrate the nature of the .thrustbearing 16. Thrust bearing 16 includes thrust surface 17 having aplurality of radially extending grooves 20. These grooves and adjacentportions may be better seen in FIGURE 4 which thrust member 16 whereinthrust surface 17' includes a plurality of arcuate grooves 20 whichextend in a direction whereby the friction effect of rotating surfaceurges air through said grooves. Adjacent grooves 20. are inclinedsurfaces 21 constructed similar to surfaces 21 in FIGURE 4 andsimilarly, there are planar portions 22 similar to surfaces 22 in FIGURE4. In this embodiment, the lubricating air to the bearing 6 is suppliedat an elevated pressure as determined by the pumping effort of thisconstruction.

In the operation of the apparatus shown in FIGURE 1, the induction motoris started and functions electrically in the manner of a conventionalmotor of this type.

Initially, the rotor 2 is supported on the upper surfacev of bearing 7in stator 9 andbecause of theplasticmaterial coated on the stator thereis maintained the desired magnetic or air gap between the rotor and thestator plus desirable low friction surface contact to permit relativemovement of the surfaces. As the rotor begins to turn, hydrodynamicfluid pressure is generated between the rotor and the stator in the airgap and the rotor assumes the eccentric position shown in FIGURE 6. Inthe converging area 25 (FIGURE 6) between bearing surface 7 and journalsurface 6, the rotation of the rotor generates a positive pressure shownby curve 27. Since diverging area 26 is an expanding space between therotor and stator, there is generated a negative pressure shown by curve23. The character of these pressurecurves is well known in the bearingart. 7 7

In the disclosed embodiment of the invention, air is supplied betweenthe journal surface 6 and bearing surface 7 by being drawn from theatmosphere through of said rotor and having grooves extending throughthe grooves in the thrust bearingshown in FIGURES 3 a and 4 andv grooves20 in the bearing shown in FIGURE 5, the air being drawn into the spacebetween the journal and the hearing by the negative pressure generatedas shown by curve 23. The rotor is then supported by positive airpressure which is hydrodynamically generated. In the present embodimentthrust bearing surfaces 17 also utilize air as a lubricant. As a resultof the inclined portions 21 and 21' there is created hydrodynamic wedgesof air between the thrustbearings and journal surfaces. In this manner,the rotor is supported hydrodynamically at the ends and in the magneticgap which eflectively floats the rotor.

The present invention presents a compact dynamoinner and outerperipheries of said thrustbearingmeans, and passage means locatedadjacent said thrust bearing means for supplying gaseous lubricant fromthe atmosphere to the bearing means by means of hydrodynamic wedges ofgaseous lubricant being generated between the thrust bearing means andthe end of the rotor.

2. In a dynamoelectric machine, the combination of a stator, a rotorinductively associated with said stator, said rotor substantiallyenveloping said stator and defining a magnetic gap therebetween, saidstator including bearing means, said rotor including journal meansoperatively associated in said magnetic gap with said bearing means, athrust bearing adapted to engage the end of said rotor, said thrustbearing having inclined portions and groove means extending through theinner and outer peripheries of said thrust bearing means and adapted togenerate hydrodynamic wedges of gaseous lubricant and to place themagnetic gap in communication with the atmosphere to supply gaseouslubricant from the atmosphere to the bearing means.

3. The dynamoelectric machine according to claim 2 in which the groovemeans comprise a plurality of radially extending grooves extendingthrough the bearing surface of the thrust bearing means.

4. The dynamoelectric machine according to clairnZ in which the groovemeans comprise a plurality of armate grooves in the thrust bearingsurface of the bearing means for placing the bearing means incommunication with the atmosphere. V

5. In a'dynamoelectric machine, the combination of a stator havingwindings, said stator having an outer cylindrical surface with anonmagnetic coating, said coated surface comprising a bearing surface, arotor inductively associated with said stator, said rotor having aninner cylindrical surface defining a journal surface to engage thebearing surface of said stator, said rotor substantially enveloping saidstator and defining a magnetic gap therebetween, said stator furtherhaving planar journal surfaces located on each end thereof, thrustbearing means associated with planar journal surfaces, said thrustbearing means including surfaces having a plurality of radiallyextending grooves extending through the inner and outer peripheries ofsaid thrust bearing means and inclined portions for placing the bearingsurface located in said magnetic gap in communication with theatmosphere electriomachine havingbearings in the magnetic gap. 1 Spaceis conserved by utilizing airlubricated bearings obviating the use of alubricant reservoir in the device. Furthermore, the air is suppliedwithout auxiliary pumping means but is hydrodynamically induced into themagnetic gap. The described embodiment discloses a construction which isboth compact and highly effectivefor fan constructions, and is assuredof long life because of Y the unique bearing construction and the novelmeans with which lubricant is supplied to the bearing surfaces.

While I have describedpreferred embodiments of my invention, it will beunderstood that my invention is not limited thereto since it may beotherwise embodied within the scope of the appended claims. I

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. In a dynamoelectric machine, the combination of a stator, arotorinductively associated with said stator, said rotor substantiallyenveloping said stator and defining a magnetic gap therebetween, saidstator including bearing means, said rotor including journal meansoperatively associated in said magnetic gap with said bearing I means,thrust bearing means adapted to engage the end whereby gaseous lubricantfrom the atmosphere passes through the said groove and provideslubricant for said bearin g surface.

' References tlited inthe file of this patent UNITED STATES PATENTS2,362,667 Schmidt Nov. 1, 1944 2,427,947 Koch Sept. 23, 1947 2,495,895,Hervert Ian. 31, 1950 2,713,970 Kueser July 26, 1955 2,802,957 GieversAug. 13, 1957 2,854,188 Shomphe Sept. 30, 1958 2,889,474 Macks June 2,1959 2,916,642 Macks Dec. 8, 1959 2,929,944 Shewmon Mar. 22, 19602,937,294 Macks May 17, 1960 2 2,951,634 Koch Sept. 6, 1960 2,983,832Macks May 9, 1961 3,004,180 Macks Oct. 10, 1961 3,022,935 Frost Feb. 27,1962 Burgwin etal. i Mar. 27, 1962

1. IN A DYNAMOELECTRIC MACHINE, THE COMBINATION OF A STATOR, A ROTORINDUCTIVELY ASSOCIATED WITH SAID STATOR, SAID ROTOR SUBSTANTIALLYENVELOPING SAID STATOR AND DEFINING A MAGNETIC GAP THEREBETWEEN, SAIDSTATOR INCLUDING BEARING MEANS, SAID ROTOR INCLUDING JOURNAL MEANSOPERATIVELY ASSOCIATED IN SAID MAGNETIC GAP WITH SAID BEARING MEANS,THRUST BEARING MEANS ADAPTED TO ENGAGE THE END OF SAID ROTOR AND HAVINGGROOVES EXTENDING THROUGH THE INNER AND OUTER PERIPHERIES OF SAID THRUSTBEARING MEANS, AND PASSAGE MEANS LOCATED ADJACENT SAID THRUST BEARINGMEANS FOR SUPPLYING GASEOUS LUBRICANT FROM THE ATMOSPHERE TO THE BEARINGMEANS BY MEANS OF HYDRODYNAMIC WEDGES OF GASEOUS LUBRICANT BEINGGENERATED BETWEEN THE THRUST BEARING MEANS AND THE END OF THE ROTOR.